title: Claudin-2 expression increases tumorigenicity of colon cancer cells: role of epidermal growth factor receptor activation.
abstract: Claudin-2 is a unique member of the claudin family of transmembrane proteins, as its expression is restricted to the leaky epithelium in vivo and correlates with epithelial leakiness in vitro. However, recent evidence suggests potential functions of claudin-2 that are relevant to neoplastic transformation and growth. In accordance, here we report, on the basis of analysis of mRNA and protein expression using a total of 309 patient samples that claudin-2 expression is significantly increased in colorectal cancer and correlates with cancer progression. We also report similar increases in claudin-2 expression in inflammatory bowel disease-associated colorectal cancer. Most importantly, we demonstrate that the increased claudin-2 expression in colorectal cancer is causally associated with tumor growth as forced claudin-2 expression in colon cancer cells that do not express claudin-2 resulted in significant increases in cell proliferation, anchorage-independent growth and tumor growth in vivo. We further show that the colonic microenvironment regulates claudin-2 expression in a manner dependent on signaling through the EGF receptor (EGFR), a key regulator of colon tumorigenesis. In addition, claudin-2 expression is specifically decreased in the colon of waved-2 mice, naturally deficient in EGFR activation. Furthermore, genetic silencing of claudin-2 expression in Caco-2, a colon cancer cell line, prevents the EGF-induced increase in cell proliferation. Taken together, these results uncover a novel role for claudin-2 in promoting colon cancer, potentially via EGFR transactivation.
authors.affiliation: Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: P
authors.initials: P
authors.lastname: Dhawan
authors.forename: R
authors.initials: R
authors.lastname: Ahmad
authors.forename: R
authors.initials: R
authors.lastname: Chaturvedi
authors.forename: J J
authors.initials: JJ
authors.lastname: Smith
authors.forename: R
authors.initials: R
authors.lastname: Midha
authors.forename: M K
authors.initials: MK
authors.lastname: Mittal
authors.forename: M
authors.initials: M
authors.lastname: Krishnan
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Eschrich
authors.forename: T J
authors.initials: TJ
authors.lastname: Yeatman
authors.forename: R C
authors.initials: RC
authors.lastname: Harris
authors.forename: M K
authors.initials: MK
authors.lastname: Washington
authors.forename: K T
authors.initials: KT
authors.lastname: Wilson
authors.forename: R D
authors.initials: RD
authors.lastname: Beauchamp
authors.forename: A B
authors.initials: AB
authors.lastname: Singh
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002455:Cell Division / Q000235:genetics; D057167:Claudins; D003110:Colonic Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics*; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000209:etiology / Q000235:genetics / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: C491875:CLDN2 protein, human; D057167:Claudins; D008565:Membrane Proteins; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D011494:Protein Kinases; D066246:ErbB Receptors; D005472:Fluorouracil